Dielectric thin film element, piezoelectric actuator and liquid discharge head, and method for manufacturing the same

Abstract

In piezoelectric thin films constituting crystalline dielectric thin film elements used for a piezoelectric actuator of a liquid discharge head, stress is generated in the crystallization step by heating due to the lattice misfit. Given this fact, by interposing between a substrate and intermediate layer which has a twin structure that absorbs the stress, film peeling and deterioration of the piezoelectric properties of the piezoelectric thin films are prevented. The intermediate layer is of a multi-layer structure which has a first intermediate layer comprising a twin structure thin film and a second intermediate layer which is the lower electrode, and because the substrate also serves as a lower electrode, the intermediate layer has a single layer structure comprising a twin structure thin film.

1. A dielectric thin film element comprising:
 an intermediate layer formed on a substrate; and 
 a single crystal or single oriented dielectric thin film formed on the intermediate layer, 
 wherein the intermediate layer has a twin structure having a twin plane. 
 
     
     
       2. A piezoelectric actuator comprising:
 a vibrating plate; 
 an intermediate layer formed on the vibrating plate; and 
 a single crystal or single oriented piezoelectric thin film formed on the intermediate layer, 
 wherein the intermediate layer has a twin structure having a twin plane. 
 
     
     
       3. The piezoelectric actuator according to  claim 2 , wherein the piezoelectric thin film is a lead piezoelectric thin film and wherein the intermediate layer has a thin film of PbTiO 3  or SrRuO 3 . 
     
     
       4. A liquid discharge head which pressurizes liquid in a pressure chamber by a piezoelectric driving force to discharge the liquid through a discharge port, said head comprising:
 a flow path substrate equipped with the pressure chamber; 
 a vibrating plate provided corresponding to the pressure chamber; 
 an intermediate layer formed on the vibrating plate; 
 a single crystal or single oriented piezoelectric thin film formed on the intermediate layer; and 
 an electrode for supplying current to the piezoelectric thin film, 
 wherein the intermediate layer has a twin structure having a twin plane. 
 
     
     
       5. The liquid discharge head according to  claim 4 , wherein the intermediate layer has a tetragonal thin film and ( 001 ) is the main growing plane. 
     
     
       6. The liquid discharge head according to  claim 4 , wherein the intermediate layer has an orthorhombic thin film and ( 001 ) is the main growing plane. 
     
     
       7. The liquid discharge head according to  claim 4 , wherein the intermediate layer has a thin film of PbTiO 3  or SrRuO 3 . 
     
     
       8. The liquid discharge head according to  claim 4 , wherein the twin plane of the intermediate layer is ( 101 ) or ( 011 ). 
     
     
       9. The liquid discharge head according to  claim 4 , wherein the thin film having a twin structure has a film thickness of 1 to 200 nm.